Alcohol ingestion, either in the acute or chronic states, has been demonstrated to be associated with an increased incidence of bacterial infections which are generally more severe in nature than in the non-alcoholic, denoting the presence of an alcohol-mediated alteration in host defense mechanisms. The research study is designed to evaluate the influence of acute and chronic ethanol exposure on varying functional expressions of the reticuloendothelial system (RES), a fundamental host defense mechanism. These studies, with both clinical and experimental phases, will include ascertaining the influence of alcohol on macrophage phagocytosis, killing ability, intracellular digestion, and antigen processing in both and in vitro and in vivo systems. The antigen processing studies will define mechanisms of impaired immune response while the studies on phagocytosis, killing and digesting of bacteria will clarify ethanol induced mechanisms of decreased resistance to infection. Since fatty acid esters, compounds which have been demonstrated to profoundly impair RE function, have been reported to occur in plasma after acute ethanol ingestion, studies will be undertaken to evaluate the role of fatty acid esters as mediators of altered RE function in acute and chronic alcoholics, as well as ascertaining their role in alcohol-induced infectious states.